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Old 16th Jul 2018, 1:17 pm   #1
Giulio Maiocco
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Default Philips K6 and K7 strange fault(s)

Good afternoon everybody.

Sorry to bother, but I bought a while ago these 2 TV sets, yes, they have valves inside and yes, they are colour! But... The K6 came from Germany, where my German friend cleaned it and made it work. Then another good friend from Milano went to Germany with his truck and brought back lots of these beauty in Italy, He knows how to handle these sets and he uses the utmost care, he is a collector himself. About the K7, I took it from my friend in Milano and I saw it working very good indeed, only few cold solder joints in the convergence PCB I still need to attend to. Time to arrive home, place it at its place, switch it on and the problem manifested itself right away.

Basically both sets do the same thing, it's a green-ish horizontal band slowly rolling down the screen and there is no colour, the b&w/colour switch does nothing, as you never hear the classic "click" of the relay when these sets operate normally.

These are 2 videos I uploaded on Youtube, if they are of any help:

K6: https://youtu.be/p-RR9z4C49s
K7: https://youtu.be/YyS6RVl57xw

Please, could some kind soul help me fix these sets? I know next to nothing about solid state stuff and PCB technology does not help me trying to follow the circuit

Best regards from Italy
Giulio Maiocco
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Old 16th Jul 2018, 6:24 pm   #2
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Default Re: Philips K6 and K7 strange fault(s)

Hi
It seems very odd that both these TVs are doing much the same thing. Are you sure your signal is OK? Is there any difference if you turn the colour controls down?
It doesn't look like any decoder fault that I'm familiar with.
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Old 16th Jul 2018, 6:25 pm   #3
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Default Re: Philips K6 and K7 strange fault(s)

Buona sera Giulio amico mio!

First video looks like a kind of hum, because the color field moves from the top to the bottom.
Looks like a pleasure for a tele man!

I shall try to find something out for you!

Ciao,
German Dalek
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Old 16th Jul 2018, 7:28 pm   #4
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Default Re: Philips K6 and K7 strange fault(s)

I may be talking rubbish but isn't this what happens if the set is SECAM being used on a PAL signal ?
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Old 16th Jul 2018, 7:34 pm   #5
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Default Re: Philips K6 and K7 strange fault(s)

Never any rubbish Stephen. Many a complicated fault can have a very simple answer. John.
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Old 16th Jul 2018, 10:48 pm   #6
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Default Re: Philips K6 and K7 strange fault(s)

Hi,
I just wondered what signal source you were feeding into both sets ? And are you using a separate modulator ?
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Old 17th Jul 2018, 6:10 am   #7
Giulio Maiocco
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Default Re: Philips K6 and K7 strange fault(s)

Good morning to all of you!

Very interesting fault, isn't it?

Well, I'm feeding the sets with two RF modulators, as one is in the laboratory and the other one, the smaller K7, is in my room. I used both modulators on a Saba T2500 colour set I had and regret exchanging to the K7 and a small amount of cash (a beast equipped with 24 valves and 2 separate EHT transformers), and they both gave fantastic results, so I would be inclined to say that my problem is not coming from there.

No, the colour control has no effect and the "rotating bar" is still present with no antenna connected to the TV, at least on the K6

Thorsten, you are right, this is a joy for a teleman

Best regards

Giulio
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Old 17th Jul 2018, 6:43 am   #8
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Default Re: Philips K6 and K7 strange fault(s)

Buona giornata Giulio!

I placed a request in the dutch Forum with a link to this place.
I get some answers, some gave advice which doesn`t help,
it was advice to use a transformer when working on the set,
questions about your Video source, maybe NTSC problems
and so on.
But it has to be clear, just because the video is synchronized
in italian language, that this is not a NTSC source.

Btw. I loved that sexy girl from "The Dukes of Hazzard" and J.D. Hogg
with his white Cadillac convertible.

This could help you, so I hope:
- check the PTC resistor for the CRT disgussing, make a special disgussing
- is your b/w picture really b/W?
- it seems that the voltage for the CHROMA assy. is not good rectified

Henk gives that advice:
door henkk @, 17.07.2018, 07:33 (6 minuten geleden) @ Adelbert

Bij de K6 werkt de hulpdraaggolfoscilator niet,geen 4,43 MHz spanning op punt 1van U630.
Als deze spanning wel aanwezig is is een van de spoeltjes in U630 onderbroken.
De hulpdraaggolfoscilator moet ook werken als er geen kleursignaal aanwezig is anders zweven de ingangen van de kleurverschilversterkertjes,de bromspannig wordt begrenst door de detectiediodes waardoor dit een prachtige 50 Hz blok wordt.
Dit geeft die mooie kleurbalk die door het beeld loopt.
Eenvoudig gezegd dus:als er geen kleur is maar wel kleurbalk werkt de hulpdraaggolfoscilator niet en kan een PCF 802 nog wel uitkomst brengen,ieder geval daar zoeken.
Als er wel (foute) kleur is en tevens lopende kleurbalk is U630 (een van de spoeltjes) defect.
Leuke fout,heb ik ook wel eens gehad.
Bij de K7 lijkt afgezien van andere dingen die je niet goed kan zien op de gammele video dat de helderheid van links naar rechts verloopt.
Dit komt door een capaciteitsloze elco C682,120 uF van de AVR.Heel eventueel ook C677.
Hierdoor komt een prachtige lijnfrequente zaagtand over de AVR te staan,waardoor dit irritante beeld.

Henk

It is in dutch, I am now to short in time, have to work now, but you can
translate it into english or italian with goolge translate.
If it is not clear, feel free to ask me, I can translate, too.

Good luck!
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Last edited by German Dalek; 17th Jul 2018 at 6:52 am.
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Old 17th Jul 2018, 7:15 am   #9
Giulio Maiocco
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Default Re: Philips K6 and K7 strange fault(s)

Hey Thorsten,

I translated what Henk wrote, and this is interesting...

I do have the negative voltage on the PCF802 4,43Mhz oscillator, so this should be operative. I should check for signal at pin 1 of U630 with the 'scope, but what if the transformer inside U636 is somehow misaligned? What would be the symptom? I should also check for micro cracks in the tracks leading to U630 and the oscillator.

I will also replace the 2 elko in the K7 and see what happens

Best
Giulio
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Old 17th Jul 2018, 7:21 pm   #10
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Default Re: Philips K6 and K7 strange fault(s)

Here is more news:
douwebakker wrote:
My free translation:
The 4,43 MHz signal has to run synchronish, in the front porch/entry amp
for the video signal is a reference burst signal, it has to be about 6-8
periodes, will these signals recognized?

Good luck

Another member is asking if you signal is really good, he cant believe that both sets have about the same issue.
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Old 18th Jul 2018, 11:34 am   #11
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Default Re: Philips K6 and K7 strange fault(s)

More news from Henkk:

If U 636 is not right aligned, you have no colour! That means no colour bar at all!
In that case U 630 seems to be bad.
It is possible to control the little coils from U 630. If you need one, he will
help you with one.
Another possibility is a broken solder line between U 630 and the PCF 200,
but that issue is typical for U 630.

Ciao,
German Dalek
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Old 18th Jul 2018, 11:45 am   #12
Giulio Maiocco
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Default Re: Philips K6 and K7 strange fault(s)

Hi Thorsten,

what you posted is really appreciated and really interesting to boot!

So, if I have a little spare time this weekend, I'll look for a 38Vpp sinewave at pin 1 of U630 and I'll check for broken traces on the circuit board leading to the PCF200 tube and around U630 itself. Rewinding these little coils in the event one or more than one is broken should not be so bad, I think, but if worst come to worst, I'll ask for Henk's help

Correct me if I'm wrong, please... You said that if U636 is misaligned, I would not get colour, not even the rolling bar. So this implies that the 4,43 Mhz oscillator does indeed work, right?

Cheers

Giulio
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Old 18th Jul 2018, 2:51 pm   #13
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Default Re: Philips K6 and K7 strange fault(s)

Hi Giulio!
Exactly! That is what Henk wrote.
Do you have a clean schematic for this set?

Btw., what is your fat cat doing?

Ciao,
German Dalek
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Old 18th Jul 2018, 3:20 pm   #14
Giulio Maiocco
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Default Re: Philips K6 and K7 strange fault(s)

Ok Thorsten, so this information should render more manageable tracking down the fault(s)

Yes, I do have a good schematic for the generic K6 chassis, I believe they are all about the same, one major difference is the use of the PL504 and PL509 in later sets vs. the PL500 and PL505 in earlier sets like mine uses.

Really that much time elapsed since we met during your tour in Italy? My fat cat (17 Kg) passed away 10 years ago and his "substitute" recently, too!
Now we are down to 2 cats at my place, maybe I should take another one in?

Cheers my friend.. and BTW if you are planning to come in Italy in the future, let me know

Giulio
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Old 18th Jul 2018, 4:11 pm   #15
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Default Re: Philips K6 and K7 strange fault(s)

Not being familiar with either of sets, but I see a reference to the G6. Does your two sets employ CDA output stages? The G6 was a favourite of mine and similar screen faults to the two You-tube videos suggested a clamping problem in the output stages, the Pye hybrid (s\s) suffered the same issues.
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Old 18th Jul 2018, 4:49 pm   #16
Giulio Maiocco
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Default Re: Philips K6 and K7 strange fault(s)

Good evening Tony,

Sorry to sound ignorant, what is exactly a CDA output stage? Maybe we call the same thing in a different way.

In these sets, there is a luminance valve and three smaller ones, usually 3 PCF200, are employed as B-Y, G-Y and R-Y outputs, is that the CDA you mention?

Best regards

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Old 19th Jul 2018, 6:47 am   #17
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Default Re: Philips K6 and K7 strange fault(s)

Hi Giulio!

Several people want to know if you really use a PAL source, not NTSC.
For me it is clear, because it is synchronized in italian language, common
in Italy.
I know you as a brillant techician so I am sure to know, that you don`t
use NTSC sources on a PAL set.

But why you don`t use a colour bar generator? Then it is easier to check
the set with a scope.

Ciao,
German Dalek
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Old 19th Jul 2018, 6:55 am   #18
Giulio Maiocco
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Default Re: Philips K6 and K7 strange fault(s)

Hey Thorsten,

Yes, my DVD player is for the italian market, about the DVD, a dear friend of mine here in Italy burnt it for me, so definitely PAL system is used here. I had this same setup working real good with the SABA T2500 I had before, so this shouldn't be the issue.

Ok, I can use the bar generator to take measurements, this is of course no problem. But I urge to repeat that the greenish band is present and rotating a bit faster without signal in antenna, so I can at least check the presence of the signal on pin 1 of U630 without something connected in antenna.

Cheers

Giulio
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Old 19th Jul 2018, 7:43 am   #19
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Default Re: Philips K6 and K7 strange fault(s)

Hi,

I don't know if this is any help but I also use external modulators. When analogue was still transmitting I'd get a proper colour picture but not with the modulator.

I encountered the problem with a few sets which confirmed the problem wasn't with the sets themselves.

Very slight re-adjustment of the reference oscillator coil solved the problem with the modulator.

With care the reference oscillator can be set to give full colour with off air and with the modulator.

I serviced a single standard G6 where I'd forgotten to re-check the reference oscillator setting on off air reception.

I soon got feedback to say the set was working well but with no colour. I immediately knew what had happened!

Brian
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Old 19th Jul 2018, 1:53 pm   #20
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Default Re: Philips K6 and K7 strange fault(s)

Hello, Yes, I think your'e on the right theme, CDA = colour difference amplifier. Clamping problems caused no end of strange symptoms.
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